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Re: bootp questions [was: Unidentified subject!]

Hi Vanco!

On Sun, 30 Sep 2001, vanco trencevski wrote:

> can somebody please answer me on this question: what is the minimum
> lenght of a bootp packet? what is the maximum?

I suppose you are having problems booting a client with bootp because not
all options are passed from your dhcpd/bootpd. I.e. when using no vendor
tags, everything works fine? Taking a look at the RFCs at [0]:

-- RFC1497 (which is obsoleted by RC1533) --
When selecting information to put into the vendor specific area, care
should be taken to not exceed the 64 byte length restriction. Nonessential
information (such as host name and quote of the day server) may be
excluded, which may later be located with a more appropriate service
protocol, such as RLP or the WKS resource-type of the domain name system.
Indeed, even RLP servers may be discovered using a broadcast request to
locate a local RLP server.
-- snap --

BOOTP is limited by the RFCs to 64 bytes of options. You can violate the
RFC by specifically setting the limit higher. Actually most bootp clients
expect this, because the old BSD bootpd never honored the spec (AFAIK).

* dhcpd
To violate the protocol in this way, add the following to your
dhcpd.config configuration.

option dhcp-max-message-size 1024;

* bootpd
Override the length in bootptab with :ms=1024: (or less)

Besides that -- if it's an option -- switch to isc dhcpd. You won't regret


[0] http://www.rfc-editor.org/cgi-bin/rfcsearch.pl, "bootp" search

ruehmkorf at informatik dot uni hyphen koeln dot de

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